#include <vector>
#include <algorithm>
#include <cmath>

// Define real type (float in this case)
using Real = float;

// Constants and configuration
constexpr int MAX_PROCESSES = 1024;  // Maximum number of parallel processes

class ContactSolver {
public:
    // Main solution driver routine
    void solveContact(
        int isLocalContact,          // Flag for local (1) vs global (0) contact
        int contactId,               // Identifier for this contact interface
        int contactType,             // Type of contact interface
        int solutionPass,            // Current solution pass (1st or 2nd)
        int numMasterSegments,       // Number of master segments
        int numInternalSlaveNodes,   // Number of internal slave nodes
        int numGlobalSlaveNodes,     // Number of global slave nodes
        int massScalingFlag,         // Mass scaling flag
        const std::vector<Real>& nodeCoordinates, // Node coordinates (3 x NUMNP)
        const std::vector<int>& segmentConnectivity, // Master segment connectivity
        const std::vector<int>& globalNodeIds,    // Global node numbering
        const std::vector<Real>& contactParams,   // Contact parameters
        const std::vector<Real>& segmentThickness, // Segment thickness values
        const std::vector<Real>& nodeThickness,   // Node thickness values
        const std::vector<int>& slaveNodeList,    // Internal slave node list
        std::vector<int>& contactParameters,      // Integer contact parameters
        std::vector<int>& penetrationPointers,    // Pointers to penetrating nodes
        std::vector<Real>& accelerations,         // Nodal accelerations
        std::vector<Real>& velocities,            // Nodal velocities
        const std::vector<Real>& nodalMasses,     // Nodal masses
        std::vector<Real>& contactForces,         // Contact forces output
        std::vector<int>& leakFlags,              // Leakage flags
        std::vector<Real>& slaveNodeTemps,        // Slave node temperatures
        std::vector<Real>& frictionCoefficients,  // Friction coefficients
        std::vector<Real>& nodalAreas,            // Nodal areas
        const std::vector<int>& flagTable,        // Flag table
        const std::vector<int>& insectPointerList, // Pointer for insect list
        const std::vector<int>& insectProjectionList, // Projection list
        std::vector<std::array<int, 4>>& processControlData, // MPI process control
        std::vector<int>& interfaceFlags,         // Interface flags
        std::vector<Real>& pipeScaleFactors,      // Pipe scale factors
        std::vector<Real>& maxPipeValues,         // Maximum pipe values
        std::vector<Real>& pipeCounters,          // Pipe counters
        const std::vector<Real>& frictionParams,  // Friction parameters
        const std::vector<int>& contactPairs,     // Contact pairs
        std::vector<Real>& pressureLoads,         // Pressure loads
        std::vector<Real>& slaveAreas,            // Slave areas
        std::vector<Real>& thermalFluxes,         // Thermal fluxes
        std::vector<Real>& nodalTemperatures      // Nodal temperatures
    ) {
        // Local variables
        int totalContactPairs = 0;       // Total number of contact pairs
        int maxPairsPerProcess = 0;      // Maximum pairs per parallel process
        int currentIteration = contactParameters[8]; // Current iteration count
        int contactAccelerator = contactParameters[9]; // Contact search accelerator
        int pipeContactFlag = contactParameters[14]; // Pipe contact flag
        int edgeDeletionFlag = contactParameters[17]; // Edge deletion flag
        int maxBuckets = contactParameters[18]; // Maximum buckets for spatial search
        int leakDetectionFlag = contactParameters[91]; // Leak detection flag
        int thermalForceFlag = contactParameters[94]; // Thermal force flag

        // Real parameters
        Real scaleFactor = contactParams[0]; // Contact scale factor
        Real frictionCoeff = contactParams[1]; // Friction coefficient
        Real contactThickness = contactParams[2]; // Contact thickness
        Real dampingFactor = contactParams[8]; // Damping factor
        Real initialThickness = contactParams[9]; // Initial thickness
        Real contactStiffness = contactParams[10]; // Contact stiffness
        Real nonlinearScale = contactParams[19]; // Nonlinear scale factor
        Real thicknessExtension = contactParams[23]; // Thickness extension

        // Special handling for initial cycle
        int removeInitialPenetration = 0;
        if (currentCycle_ == 0 && contactParameters[92] == -99) {
            removeInitialPenetration = 1;
            scaleFactor = 0.0;
        }

        // Additional parameters
        int lithFlag = contactParameters[99]; // Lithography flag
        Real separationStrength = contactParams[49]; // Separation strength
        Real separationThickness = contactParams[50]; // Separation thickness
        Real thermalConductivity = contactParams[32]; // Thermal conductivity
        Real thermalSurface = contactParams[33]; // Thermal surface coefficient

        // Initialize global output values (except for second pass or type 37)
        if (massScalingFlag != -1 && contactType != 37) {
            contactForces[0] = 0.0;
            contactForces[1] = 0.0;
            contactForces[2] = 0.0;
            contactForces[3] = 0.0;
        }
        if (massScalingFlag != -1) contactParams[41] = 0.0;

        Real springWork = 0.0;  // Spring work accumulation
        Real frictionWork = 0.0; // Friction work accumulation

        // Memory allocation and management
        manageMemory(maxBuckets, numMasterSegments, numInternalSlaveNodes, 
                    totalContactPairs, maxPairsPerProcess);

        // Build contact pair list if this is the first iteration
        if (currentIteration == 1) {
            buildContactPairList(isLocalContact, totalContactPairs, nodeCoordinates,
                              segmentConnectivity, maxBuckets, globalNodeIds,
                              penetrationPointers, contactAccelerator, insectPointerList,
                              insectProjectionList, segmentThickness, nodeThickness,
                              contactThickness, numGlobalSlaveNodes, numMasterSegments,
                              numInternalSlaveNodes, flagTable, processControlData,
                              contactId, contactType, frictionCoeff, thicknessExtension,
                              separationThickness);

            // Update contact parameters
            int pairCountPosition = (solutionPass == 1) ? 10 : 11;
            contactParameters[pairCountPosition] = totalContactPairs;
            contactParameters[30] = std::max(maxPairsPerProcess, contactParameters[30]);
            contactParameters[31] = std::max(totalSlaveNodes_, contactParameters[31]);

            if (totalContactPairs > 0) {
                // Handle friction data transfer for existing contacts
                if (frictionCoeff != 0.0) {
                    transferFrictionData(totalContactPairs);
                }

                // Build segment pointer list
                buildSegmentPointerList(numMasterSegments, penetrationPointers);
            }
        }

        // Initialize friction flags if friction is active
        if (frictionCoeff != 0.0) {
            initializeFrictionFlags(totalContactPairs);
        }

        // Identify active segments (those with thickness > 0 and penetrations)
        int numActiveSegments = 0;
        for (int i = 0; i < numMasterSegments; i++) {
            if (segmentThickness[i] > 0.0 && 
                penetrationPointers[i+1] != penetrationPointers[i]) {
                activeSegments_[numActiveSegments++] = i;
            }
        }

        // Main contact force calculation
        calculateContactForces(
            isLocalContact, totalContactPairs, nodeCoordinates, velocities,
            numInternalSlaveNodes, slaveNodeList, nodalMasses, nodeThickness,
            nodalAreas, processControlData, segmentVelocityData_,
            contactPairList_, processContactList1_, processContactList2_,
            oldContactIndices_, segmentPointerList_, segmentThickness,
            segmentNormals_, segmentConnectivity, candidateSegments_,
            penetrationDistances_, segmentOrientations_, contactThickness,
            numActiveSegments, activeSegments_, segmentAreas_, pipeCounters,
            maxPipeValues, pipeScaleFactors, initialThickness, thermalForceFlag,
            numMasterSegments, frictionCoefficients, interfaceFlags,
            frictionForces_, contactOrientations_, frictionFlags_,
            nodalForces_, contactPairs, frictionParams, pressureLoads,
            dampingFactor, springWork, massScalingFlag, contactForces,
            accelerations, leakFlags, leakDetectionFlag, nonlinearScale,
            slaveNodeTemps, scaleFactor, edgeDeletionFlag, frictionWork,
            frictionCoeff, contactId, contactParams, slaveAreas,
            pipeContactFlag, contactStiffness, removeInitialPenetration,
            separationStrength, separationThickness, thermalFluxes,
            nodalTemperatures, lithFlag, thermalConductivity,
            thermalSurface, contactType, slaveTemperatures_
        );

        // Zero out friction forces for non-contacting pairs
        if (frictionCoeff != 0.0) {
            for (int i = 0; i < totalContactPairs; i++) {
                if (frictionFlags_[0][i] == 0) {
                    frictionForces_[0][i] = 0.0;
                    frictionForces_[1][i] = 0.0;
                    frictionForces_[2][i] = 0.0;
                }
                if (frictionFlags_[1][i] == 0) {
                    frictionForces_[3][i] = 0.0;
                    frictionForces_[4][i] = 0.0;
                    frictionForces_[5][i] = 0.0;
                }
            }
        }

        // Accumulate work values
        springWork_ += springWork;
        frictionWork_ += 0.5 * timeStep_ * frictionWork;
        contactForces[3] += springWork;
        contactForces[4] += frictionWork;
    }

private:
    // Member variables
    int currentCycle_;                // Current simulation cycle
    Real timeStep_;                   // Current time step size
    Real springWork_;                 // Total spring work
    Real frictionWork_;               // Total friction work
    int totalSlaveNodes_;             // Total slave nodes (internal + remote)
    
    // Contact data structures
    std::vector<int> contactPairList_;       // List of contact pairs
    std::vector<int> segmentPointerList_;    // Segment pointers
    std::vector<int> activeSegments_;        // Active segments list
    std::vector<int> oldContactIndices_;     // Old contact indices
    std::vector<int> frictionFlags_[2];      // Friction update flags
    
    // Physical data
    std::vector<Real> penetrationDistances_; // Penetration distances
    std::vector<Real> segmentNormals_;       // Segment normal vectors
    std::vector<Real> segmentAreas_;         // Segment areas
    std::vector<Real> frictionForces_[6];    // Friction forces storage
    std::vector<Real> segmentVelocityData_;  // Segment velocity data
    std::vector<Real> slaveTemperatures_;    // Slave node temperatures
    
    // Parallel processing data
    std::vector<int> processContactList1_;   // Process contact list 1
    std::vector<int> processContactList2_;   // Process contact list 2
    std::vector<int> candidateSegments_;     // Candidate segments
    
    // Helper methods
    void manageMemory(int maxBuckets, int numSegments, int numSlaveNodes, 
                     int totalPairs, int maxPairsPerProc) {
        // Implementation of memory management would go here
        // This would resize all the member vectors as needed
    }
    
    void buildContactPairList(int isLocalContact, int& totalPairs, 
                            const std::vector<Real>& nodeCoords,
                            const std::vector<int>& segmentConn,
                            int maxBuckets, const std::vector<int>& globalNodeIds,
                            const std::vector<int>& penetrationPtrs,
                            int contactAccelerator, const std::vector<int>& insectPtrs,
                            const std::vector<int>& projectionList,
                            const std::vector<Real>& segThickness,
                            const std::vector<Real>& nodeThickness,
                            Real contactThickness, int numGlobalSlaves,
                            int numSegments, int numSlaves,
                            const std::vector<int>& flagTable,
                            std::vector<std::array<int, 4>>& procControl,
                            int contactId, int contactType, Real frictionCoeff,
                            Real thicknessExt, Real separationThick) {
        // Implementation of contact pair search would go here
    }
    
    void transferFrictionData(int totalPairs) {
        // Implementation of friction data transfer would go here
    }
    
    void buildSegmentPointerList(int numSegments, const std::vector<int>& penetrationPtrs) {
        // Implementation of segment pointer list construction would go here
    }
    
    void initializeFrictionFlags(int totalPairs) {
        // Implementation of friction flag initialization would go here
    }
    
    void calculateContactForces(/* large parameter list */) {
        // Implementation of main contact force calculation would go here
    }
};